A process for dissolving cellulose and several cellulose derivatives having strong intermolecular hydrogen bonding in a tertiary amide oxide is disclosed by Johnson in U.S. Pat. No. 3,447,939. A cyclic mono(N-methylamine-N-oxide) compound such as N-methylmorpholine N-oxide is used as the solvent. The solution can be used in chemical reactions involving the dissolved polymer or to precipitate the polymer to form a film or filament. The resulting solutions, insofar as the actual examples of the patent indicate, have significant disadvantages because they are of low solids content and have a high viscosity.
In accordance with the process disclosed in U.S. Pat. No. 3,508,941, two or more different polymers are dissolved in a cyclic mono(N-methylamine N-oxide) compound and are precipitated together to produce a bicomponent polymer mixture. A diluent such as dimethyl sulfoxide, N-methylpyrrolidone or sulfolane may be added to the solution as a diluent to reduce its viscosity. The solutions also have the same deficiences noted for the first mentioned patent.
U.S. Pat. No. 4,145,532 and copending application Ser. No. 938,907, filed Sept. 1, 1978, to the inventors herein, discloses cellulose solutions and precipitated cellulose articles formed from a tertiary amine oxide solvent containing up to about 29% water.